textproduct: Albany

WHAT HAS CHANGED

Wind Advisory issued for all of eastern New York and western New England for Thursday Night through late Friday evening.

KEY MESSAGES

1. Warming temperatures ahead of a strong cold front will lead to a period of rain and snow melt for Thursday night into Friday morning.

2. There is the possibility for some urban and poor drainage flooding due to the rain and snowmelt early Friday.

3. Strong winds are likely Thursday night into Friday, especially for high terrain areas, which may result in downed trees and power lines.

4. Frigid conditions return Friday night into the weekend and accumulating light snow will be possible through early next week for much of the area.

DISCUSSION

KEY MESSAGE 1... A strong area of low pressure will be moving across the Upper Midwest and Great Lakes for Thursday, before heading across Ontario for Thursday Night and moving eastward through Quebec on Friday. The system will drag a strong cold front across the area. Ahead of the front, models continue to advertise a strong low-level jet. 850 hpa southerly winds will increase to 50 to 80 kts, allowing for milder air to surge into the region. Although model soundings continue to indicate a low level inversion in place, 850 hpa temps look to warm to +4 to +8 C ahead of the front for early Friday morning. Temps will initially be in the 20s for Thursday morning but should gradually warm into the 30s through the day, with even some low 40s by evening for valley areas thanks to a developing southerly breeze. Temps will follow a non-diurnal pattern on Thursday night, with the southerly flow allowing for temps to continue to warm well into the 40s across the entire are by late Thursday night, although sheltered areas will take the longest to warm up. Some valley areas may spike in low to possibly middle 50s for first thing Friday morning before the front crosses from west to east. Behind the front, temps will crash back down, with temps falling below freezing across higher elevations of the Adirondacks by the early afternoon hours. Lower terrain and eastern areas will take longer to cool, but all areas will be down into the 20s to lower 30s by late Friday evening.

Although some showers are expected by Thursday evening, most of the precip will be occurring after midnight Thursday night and will be done by noon Friday, ending from west to east. The precip may briefly end as some wet snow as colder air rushes in for the Adirondacks and Greens, with an inch or two of accumulation. Most areas will see about an inch of rainfall. NBM continues to remain very consistent with about 50% to 80% chance of 1" for most of the area, but probabilities drop considerably for 2", with most of the region under a 10% chance for greater than 2 inches. While a rumble of thunder can't be totally ruled out, the best elevated instability will be located south of the region, closer to the coast and no surface-based instability will be in place.

KEY MESSAGE 2... The rainfall will combine with some snowmelt to runoff into area rivers and streams. High terrain areas may not see much snowmelt, as the snowpack will need to ripen and the rainfall may be absorbed by the snowpack, especially in the Adirondacks and Greens where the snowpack is deeper. Valley areas may start to lose the snowpack, although it has much less water content compared to the high terrain. Nohrsc shows less than 1" of water in most valley areas snowpack at this time. As a result, the brief nature of the warmup and limited runoff probably won't be enough to move ice on the larger rivers. However, smaller streams, especially in lower terrain areas, may see some ice movement and river rises. Ice or snow piles may block drainage in urban and low lying areas and the ground is frozen. Based on this, some ponding of water is likely on roadways, in farm fields and other low spots or where infrastructure causes typical issues. The main impacts will be first thing on Friday morning during the most intense rainfall, when rates may exceed 0.25" per hour.

KEY MESSAGE 3... Strong low level jet will be moving across the region just along/ahead of the cold front for late Thursday night into Friday morning. The winds within the low level jet are as high as 80 kts, which is about 2-3 STD above normal according to the 00z NAEFS. The low-level inversion should help prevent most of these winds from mixing down, but it's possible some gusts do mix down within some heavier showers just ahead of the cold front. In addition, the s-se flow downslopes across the high terrain of the Taconics, Berkshires and Greens, so some locally high gusts are possible on the western slopes of these high terrain areas, especially if any breaks of precip occur. 3km HRRR and NAM do show some gusts reaching 50-55 mph in these areas. Overall, all areas will have a chance for some gusts over 40 mph, but the max gusts may for these localized high terrain spots of western New England or the Taconics.

In addition, all areas will be seeing widespread westerly winds behind the front for Friday afternoon through late Friday evening, as the cooler air allows for better low level mixing within the strong pressure gradient behind the departing storm. Westerly winds will also be gusting over 40 mph, especially for the high terrain, Mohawk Valley and Capital Region.

Based on all of this, have gone with a Wind Advisory for the entire area for Thursday night through late Friday evening. Highest winds will initially be late Thursday night and early Friday morning, especially eastern high terrain areas, from the south to southeast. Second round of strong winds from the west will occur on Friday afternoon and evening for much of the area. Downed trees and power lines are possible with these winds. May need to consider a focused High Wind Warning for some of the eastern areas, although some uncertainty remains about max gust potential and mixing potential within the rainfall and inversion, but there is good confidence on widespread gusts of 40 to 50 mph.

KEY MESSAGE 4... Behind this system, colder air will be returning to the region for Friday night into Saturday. After morning lows in the teens and 20s, highs will be in the upper 20s to mid 30s for Saturday. Any lingering wet surfaces Friday night may freeze over, although the wind should help dry things out. A clipper may bring some light snow showers or squalls for Saturday night into Sunday, but this will be a moisture starved northern stream frontal system, so little total snowfall is expected. However, it will reinforce the cold air for Monday, with another cold day expected with highs below freezing across the entire region. Looking ahead, another northern stream system may bring a widespread light accumulating snow on Tuesday, although confidence on this is not high this far out, as models have had varying solutions regarding storm track and precip amounts. However, this could return snow cover to the region in time for the Christmas Holiday, so will watch it closely for that potential.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through 18z Thursday...Flying conditions are VFR at all terminals as of 12:25 PM EST. While a few light rain/snow showers are possible at ALB/GFL within the first hour or two of the TAF period (hence mention of VCSH in these TAFs), mainly VFR conditions are expected this afternoon and evening with SCT to BKN mid-level clouds. Clouds diminish tonight, with skies becoming mainly clear for the second half of the night. There is a low chance for some patchy fog/mist late tonight, mainly at GFL, but confidence is too low to mention anything in the TAFs at this time. Aside from any fog/mist late tonight, VFR conditions continue through at least 18z tomorrow with mainly just high clouds around tomorrow morning.

Winds will be from the S/SE to start the TAF period this afternoon with some gusts of 15-20 kt at ALB/PSF/POU. Winds veer to the S/SW around sunset ahead of a cold front with diminishing gusts, then shift to the west behind the front between roughly 22-02z from west to east this evening. Winds behind the front will be at around 10 kt, with gusts of 20-25kt at ALB/PSF. ALB/PSF will also have some LLWS concerns with the low-level jet strengthening to 40-45kt behind the cold front. Winds, gusts, and the low-level jet all diminish after midnight, with mainly light and variable winds through early to mid-morning tomorrow. Then, winds increase around 5 kt from the S/SE at GFL/POU and 10kt at ALB/PSF with gusts to 20-25kt at ALB/PSF through 18z tomorrow. Strengthening low-level jet will lead to renewed LLWS concerns at all terminals tomorrow mid-morning through at least 18z.

Outlook...

Thursday Night: High Operational Impact. Windy With Gusts To 38 kts. Definite RA. Friday: High Operational Impact. Windy With Gusts To 38 kts. Definite RA...SN. Friday Night: Moderate Operational Impact. Windy With Gusts To 38 kts. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: Moderate Operational Impact. Chance of RA...SN. Sunday: Low Operational Impact. Breezy. Slight Chance of RA...SN. Sunday Night: Low Operational Impact. Breezy. NO SIG WX. Monday: No Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Wind Advisory from 7 PM Thursday to 1 AM EST Saturday for CTZ001-013. NY...Wind Advisory from 7 PM Thursday to 1 AM EST Saturday for NYZ032-033-038>043-047>054-058>061-063>066-082>084. MA...Wind Advisory from 7 PM Thursday to 1 AM EST Saturday for MAZ001-025. VT...Wind Advisory from 7 PM Thursday to 1 AM EST Saturday for VTZ013>015.